The present invention pertains to a cutting insert to be used in cutting tools for chip-forming machining operations. More particularly, the present invention relates to a cutting insert having a top and bottom surfaces with radially aligned chip forming grooves for effective chip control.
It is well known that in the design of cutting inserts and their mounting in a cutting tool, the provision of suitable cutting rake and relief clearance angles so as to ensure effective cutting with minimal energy consumption have to be balanced against undue weakening of the cutting edge. At the same time, provision must always be made for the effective removal of the chips generated in the cutting process. This latter requirement is particularly vital where the cutting tool operates in a very confined space, such as in a drilling operation.
The effective removal of the generated chips is to a large extent is dependant on the design of effective chip control to ensure that the generated chips are diverted from the cutting area by being deformed, split or broken into relatively short chips with minimal energy consumption and with effective heat dissipation.
To this end, it is well known to provide an insert with suitably formed depressions or grooves or with protrusions near the cutting edge which is designed to deform, split or break the chip with minimal energy consumption and with effective heat dissipation.
For example, U.S. Pat. No. 4,215,957 discloses a substantially flat rake surface of an insert which has a succession of depressions spaced along the cutting edge by substantially wide intermediate portions of the rake surface.
In U.S. Pat. No. 5,695,303, there is disclosed a cutting insert with undulating concave chip forming grooves comprising a succession of alternating depressed and raised portions extending in a direction perpendicular to the cutting edge along the entire width of the chip forming groove.
However, an effective control of chip orientation to a great extend depends on the positioning of the insert in the tool due to the specific shape of the chip forming groove and the smooth transitions between different portions thereof.
Thus, it may very often happen, particularly with cutting inserts positioned in a cutting tool at negative rake angles, that the chips cut by the cutting edge will be deflected in the direction towards, rather than away from a workpiece. Consequently, damage to the workpiece and tool chattering is possible. Thus, it would be desirable to provide an indexable cutting insert having a chip forming groove for providing effective chip control.
An object of the invention is to provide a cutting insert for use in a cutting tool having a chip forming groove for providing effective chip control.
It is another object of the invention to provide a double-sided indexable cutting insert having a chip forming groove enabling an effective chip control.
In one aspect of the invention, a cutting insert includes an upper surface, a lower surface and side surfaces. The cutting insert comprises at least one cutting edge formed at an intersection between the upper surface and one side surface. The at least one cutting edge extends between two adjacent cutting corners of the insert. The cutting insert also comprises at least one rake face adjacent the at least one cutting edge. The at least one rake face being formed with a first undulated chip forming groove extending along the at least one cutting edge and comprises alternating depressed and raised portions smoothly merging with one another. Each depressed and raised portion of the first chip forming groove is radially aligned with a central axis of the insert.
In another aspect of the invention, a cutting insert has an upper surface, a lower surface and side surfaces. The cutting insert comprises at least one cutting edge formed at an intersection between the upper surface and one side surface, at least one rake face adjacent the at least one cutting edge, a first undulated chip forming groove being formed on the at least one rake face and extending along the at least one cutting edge, a seating surface projecting above the cutting corners of the insert, and a second undulated chip forming groove extending along said seating surface. The first and second undulated chip forming grooves comprise alternating depressed and raised portions smoothly merging with one another, wherein each depressed and raised portion of the first and second chip forming grooves is radially aligned with a central axis of the insert.